Distraught dad Kevin Krim told his sisters he couldn't bear to speak to his own parents about the tragedy because he knows he'll break down, Krim's father said.

"Our son texted our daughters to say, 'I can't talk to Mom and Dad right now because I'll just fall apart,'" William Krim told DNAinfo.com New York. "He said he has to be strong for his wife and his middle daughter that survived the killing."

Kevin Krim's wife, Marina Krim, returned to their Upper West Side apartment Thursday evening to find the nanny, Yoselyn Ortega, slashing her own neck and slitting her wrists, police said. Marina then rushed to the bathroom to discover her 2-year-old son, Leo, and 6-year-old daughter, Lucia, lying in a pool of blood in the bathtub and covered in stab wounds, police said.

Kevin Krim, 37, learned of the horror from detectives Thursday night at JFK Airport after returning from a business trip, police said.

"It's so disastrous and so brutal and ugly," William Krim, 74, said from his Camarillo, Calif., home. He said he and his wife are flying to New York Saturday to be with the family.

"I honestly think I'll just be really quiet," he said. "I'll let them carry the conversation."

The grandfather said he hasn't heard from cops, but both of his daughters received calls from police and were only told that it was an accident.

"They couldn't tell us anymore," he said.

Kevin and Marina Krim, 36, hail from California. About two and a half years ago, they moved from San Francisco to a luxury apartment just a block from the American Museum of Natural History, but would make return trips to the West Coast to visit both sets of grandparents.

"My son would stay five days and then fly back to work. Then he flew back," William Krim said of his son, who works as a vice president at CNBC on the business network's digital side.

Marina received her undergraduate degree in fine arts from the University of Southern California and has a master's in education. She worked as a kindergarten teacher until she started having children. In New York City, she taught an art class and lovingly chronicled her three kids' development in a blog.

Marina and her middle daughter, 3-year-old Nessie, were at swimming lessons when the tragedy unfolded. Nanny Ortega, 50, and the two other siblings were supposed to meet the mom and their sister for ballet lessons. When they didn't show, Marina and Nessie headed back to their West 75th Street home and stumbled upon the grisly scene about 5:39 p.m.

William Krim added that his son's wife is listed in his cell phone as "Marina, Best Mother in the World."

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